Optimization of long slot-die head for Li-ion battery electrode coating

doi:10.19799/j.cnki.2095-4239.2025.0093

Abstract

Abstract:

Slot-die coating improves the production efficiency of electrode sheets, reduces material waste during coating, enhances material utilization, and lowers production costs. Wide-width coating requires efficient die heads, and the structure of the slot-die head directly affects the properties of the electrode sheets. In this study, we designed a slot-die head with a cavity length of 1520 mm and a total coating width of 1240 mm. The coating quality was evaluated using the thickness consistency of the 150 μm wet-coated layer as an indicator. The slot-die head structure was optimized in three aspects: cavity optimization, adjustment of the feed port position, and shim chamfering design. The feasibility of the optimization design was verified by tracking the start-up process of the external flow field. During the coating process with a single cavity and single-feed port (the inlet was located in the middle of the die head), the wet-coated layer was thicker in the center area and thinner in the edge area. With increasing coating width, the thickness consistency decreased significantly. However, after adding a subcavity with a coating width of 1240 mm, the wet-layer thickness consistency of slurry 1 improved from 26.88% to 9.79%. By further adjusting the single-feed inlet design to a dual-feed inlet design, the consistency of the wet-layer thickness of slurry 1 increased to 0.33%. In addition, the wall shear stress in the fluid domain at the edge of the outlet was optimized by adjusting the shim chamfering, which improved the quality of the coating edge. With a coating speed of 60 m/min and a coating width of 1240 mm, the consistency of the wet-layer thickness of slurry 1 was improved to 0.28%. The comparison of numerical simulation and experimental results showed an average relative error of only 1.35%, indicating that the slot-die structural model exhibits high accuracy. Numerical simulations of the other three viscosity slurries revealed wet-film thickness consistency in the range of 0.38%—0.58%, indicating the strong applicability of the designed model. These results serve as a reference for optimizing the design of long slot-die heads.

Key words: slot-die coating, numerical simulation, flow channel design, internal flow field, external flow field

CLC Number:

TQ 586.3

Manquan LANG, Jun YANG, Zhongchun ZHANG, Jianlin PENG, Xulai YANG. Optimization of long slot-die head for Li-ion battery electrode coating[J]. Energy Storage Science and Technology, 2025, 14(6): 2339-2351.

Figures/Tables 22

Fig. 1

Table 1

Fig. 2

Fig. 3

Fig. 4

Table 2

Fig. 5

Table 3

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Fig. 10

Fig. 11

Fig. 12

Table 4

Chamfer parameters for different sizes"

倒角类型	size1	size2	size3	size4	size5	size6	size7
$x$ /mm	1	2	3	4	5	3	3
$y$ /mm	3	3	3	3	3	2	1

Table 4

Fig. 13

Fig. 14

Fig. 15

Fig. 16

Fig. 17

Fig. 18

References 20

1	杨续来, 张峥, 曹勇, 等. 高能量密度锂离子电池结构工程化技术探讨[J]. 储能科学与技术, 2020, 9(4): 1127-1136. DOI: 10.19799/j.cnki.2095-4239.2020-0147.
	YANG X L, ZHANG Z, CAO Y, et al. The structural engineering for achieving high energy density Li-ion batteries[J]. Energy Storage Science and Technology, 2020, 9(4): 1127-1136. DOI: 10.19799/j.cnki.2095-4239.2020-0147.
2	MEI W X, CHEN H D, SUN J H, et al. The effect of electrode design parameters on battery performance and optimization of electrode thickness based on the electrochemical-thermal coupling model[J]. Sustainable Energy & Fuels, 2019, 3(1): 148-165. DOI: 10.1039/C8SE00503F.
3	罗雨, 王耀玲, 李丽华, 等. 锂电池制片工艺对电池一致性的影响[J]. 电源技术, 2013, 37(10): 1757-1759. DOI: 10.3969/j.issn.1002-087X.2013.10.015.
	LUO Y, WANG Y L, LI L H, et al. Influence of preparation techniques upon uniformity of lithium-ion batteries[J]. Chinese Journal of Power Sources, 2013, 37(10): 1757-1759. DOI: 10. 3969/j.issn.1002-087X.2013.10.015.
4	Beguin A E. Method of coating strip material: US2681294[P]. 1954-06-15.
5	DING X Y, LIU J H, HARRIS T A L. A review of the operating limits in slot die coating processes[J]. AIChE Journal, 2016, 62(7): 2508-2524. DOI: 10.1002/aic.15268.
6	迟彩霞, 张双虎, 乔秀丽, 等. 狭缝式涂布技术的研究进展[J]. 应用化工, 2016, 45(2): 360-363, 366. DOI: 10.16581/j.cnki.issn1671-3206.20151224.019.
	CHI C X, ZHANG S H, QIAO X L, et al. Research progress on slot-die coating technology[J]. Applied Chemical Industry, 2016, 45(2): 360-363, 366. DOI: 10.16581/j.cnki.issn1671-3206.2015 1224.019.
7	张红梅, 卢亚, 明五一, 等. 高速、高精智能化锂电池涂布机关键技术研究[J]. 机电工程技术, 2018, 47(7): 10-13. DOI: 10.3969/j.issn.1009-9492.2018.07.004.
	ZHANG H M, LU Y, MING W Y, et al. Research on key technology of high speed and precision intelligent lithium battery coating machine[J]. Mechanical & Electrical Engineering Technology, 2018, 47(7): 10-13. DOI: 10.3969/j.issn.1009-9492.2018.07.004.
8	RUSCHAK K J, WEINSTEIN S J. Model for the outer cavity of a dual-cavity die with parameters determined by two-dimensional finite-element analysis[J]. AIChE Journal, 2018, 64(2): 708-716. DOI: 10.1002/aic.15927.
9	LEE K Y, WEN S H, LIU T J. Vortex formation in a dual-cavity coat-hanger die[J]. Polymer Engineering & Science, 1990, 30(19): 1220-1227. DOI: 10.1002/pen.760301906.
10	杨家沐, 陈育新, 练成, 等. 电极浆料涂布模头流场分析与结构优化[J]. 储能科学与技术, 2024, 13(4): 1109-1117. DOI: 10.19799/j.cnki.2095-4239.2024.0100.
	YANG J M, CHEN Y X, LIAN C, et al. Flow field analysis and structural optimization of coating die with electrode slurry[J]. Energy Storage Science and Technology, 2024, 13(4): 1109-1117. DOI: 10.19799/j.cnki.2095-4239.2024.0100.
11	谭鹏辉. 锂离子电池极片高效挤压涂布数值模拟及工艺基础[D]. 武汉: 华中科技大学, 2022. DOI: 10.27157/d.cnki.ghzku.2022. 000208.
	TAN P H. Numerical simulation and technology foundation for efficient slot coating of lithium-ion battery electrode[D]. Wuhan: Huazhong University of Science and Technology, 2022. DOI: 10.27157/d.cnki.ghzku.2022.000208.
12	HOFFMANN A, SPIEGEL S, HECKMANN T, et al. CFD model of slot die coating for lithium-ion battery electrodes in 2D and 3D with load balanced dynamic mesh refinement enabled with a local-slip boundary condition in OpenFOAM[J]. Journal of Coatings Technology and Research, 2023, 20(1): 3-14. DOI: 10.1007/s11998-022-00660-8.
13	张剑枭, 殷德顺. 锂电池电极狭缝挤压涂布内外流场分析[J]. 能源与环保, 2023, 45(5): 161-166, 172. DOI: 10.19389/j.cnki.1003-0506.2023.05.027.
	ZHANG J X, YIN D S. Analysis on internal and external flow field in slot coating of lithium battery electrode[J]. China Energy and Environmental Protection, 2023, 45(5): 161-166, 172. DOI: 10. 19389/j.cnki.1003-0506.2023.05.027.
14	AHN W G, LEE S H, NAM J, et al. Effect of upstream meniscus shape on dynamic wetting and operating limits of Newtonian coating liquids in slot coating bead flows[J]. Journal of Coatings Technology and Research, 2018, 15(5): 1067-1076. DOI: 10. 1007/s11998-018-0059-2.
15	GABBANELLI S, DRAZER G, KOPLIK J. Lattice Boltzmann method for non-Newtonian (power-law) fluids[J]. Physical Review E, Statistical, Nonlinear, and Soft Matter Physics, 2005, 72(4 Pt 2): 046312. DOI: 10.1103/PhysRevE.72.046312.
16	黄泽湃, 杨军, 彭建林. 一种涂布湿膜厚度横向均匀性的仿真分析方法及系统. CN202310253275.5[P]. 2023-06-30.
	HUANG Z P, YANG J, PENG J L. A simulation analysis method and system for the lateral uniformity of coating wet film thickness. CN202310233275[P]. 2023-06-30.
17	彭建林, 许玉山. 一种涂布垫片、涂布模头及涂布装置: CN113275200A[P]. 2021-08-20.
	PENG J L, XU Y S. Coating gasket, coating die head and coating device: CN113275200A[P]. 2021-08-20.
18	CHANG Y R, LIN C F, LIU T J. Start-up of slot die coating[J]. Polymer Engineering & Science, 2009, 49(6): 1158-1167. DOI: 10.1002/pen.21360.
19	TEMAM R. Navier-stokes equations: Theory and numerical analysis[M]. American Mathematical Society, 2024.
20	HIRT C W, NICHOLS B D. Volume of fluid (VOF) method for the dynamics of free boundaries[J]. Journal of Computational Physics, 1981, 39(1): 201-225. DOI: 10.1016/0021-9991(81)90145-5.

符号	含义	数值/mm
L₁	进料口深度	60
L₂	腔体长度	1520
L₃	狭缝深度	60
r	进料口半径	10
R	腔体半径	25
d_single	单幅狭缝宽度(单幅涂宽)	620
h_slot	狭缝厚度	0.8

浆料编号	密度/(kg/m³)	n	K	接触角/(°)	表面张力/(mN/m)	固含量	备注
浆料1	2700	0.511	32.704	54	60	0.52	用于优化设计全过程仿真及涂布实验验证

浆料2	1350	0.555	10.521	52	49	0.50	用于优化设计方案的普适性仿真验证
浆料3	1200	0.746	11.119	55	52	0.55
浆料4	1768	0.627	45.504	63	58	0.61

副腔选型	流速匀化效果随进料口位置的影响			加工铣刀	生产工艺
副腔选型	顶部	中部	底部	加工铣刀	生产工艺
半圆柱体腔	较好	一般	较差	平底刀、圆鼻刀、球刀	加工难度大，工时长
长方体腔	较差，流速紊乱			平底刀	加工最简单，工时短
直角梯形棱柱腔	较差	一般	较好	平底刀、圆鼻刀	加工难度介于半圆柱体与长方体，工时适中

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